It is known that heteropolysaccharides can be produced by certain microorganisms. Some of such heteropolysaccharides function as hydrophilic colloids and because of their viscosity properties and rheology have been used as thickening agents for aqueous systems.
A polysaccharide of composition similar to S-156 has been described as Klebsiella pneumoniae K-type 63 (Carb. Res. (1979) 77, pp 183-190). Another is E. coli serotype K-42 (op. cit.).